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    <title>ShellCheck: SC2309 – -eq treats this as a variable. Use = to compare as string (or expand explicitly with $var)</title>
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    <h1>SC2309 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2309">See this page on GitHub</a>
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    <h2
id="-eq-treats-this-as-a-variable-use--to-compare-as-string-or-expand-explicitly-with-var">-eq
treats this as a variable. Use = to compare as string (or expand
explicitly with $var)</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2309.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">read</span> <span class="at">-p</span> <span class="st">&quot;Continue? [y/n] &quot;</span> <span class="va">var</span></span>
<span id="cb1-2"><a href="SC2309.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="st">&quot;</span><span class="va">$var</span><span class="st">&quot;</span> <span class="ot">-eq</span> <span class="st">&quot;n&quot;</span> <span class="er">​</span><span class="ex">]</span> <span class="kw">&amp;&amp;</span> <span class="bu">exit</span> 1</span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2309.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="co">#read -p &quot;Continue? [y/n] &quot; var</span></span>
<span id="cb2-2"><a href="SC2309.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="st">&quot;</span><span class="va">$var</span><span class="st">&quot;</span> <span class="ot">=</span> <span class="st">&quot;n&quot;</span> <span class="er">​</span><span class="ex">]</span> <span class="kw">&amp;&amp;</span> <span class="bu">exit</span> 1</span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>ShellCheck found a string used as an argument to a numerical operator
like <code>-eq</code>, <code>-ne</code>, <code>-lt</code>,
<code>-ge</code>. Such strings will be treated as arithmetic
expressions, meaning <code>n</code> will refer to a variable
<code>$n</code>, and <code>24/12</code> will be evaluated into
<code>2</code>.</p>
<p>In the problematic example, the intention was instead to compare
<code>"n"</code> as a string, so it should use the equivalent string
operator instead, in this case <code>=</code>.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>It is perfectly valid to use variables as operands. ShellCheck will
not flag any value that is an unquoted variable name assigned in the
script:</p>
<pre><code>a=42; [[ &quot;a&quot; -eq 0 ]]  # Flagged due to quotes
      [[ b -eq 0 ]]    # Flagged due to not being assigned
c=42; [[ c -eq 0 ]]    # Not flagged</code></pre>
<p>However, ShellCheck does not know whether you intended
<code>foo/bar</code> to be division or a file path.</p>
<p>If you intended to divide <code>$foo</code> and <code>$bar</code>,
you can either make it explicit with
<code>[[ $((foo/bar)) -ge 0 ]]</code>, or simply <a
href="ignore.html">ignore</a> the warning.</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc</li>
</ul>
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    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
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